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  • 1.
    Abbas, Nada
    et al.
    Linnaeus University, Faculty of Technology, Department of Informatics.
    Kans, Mirka
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering. Chalmers University of Technology, Sweden.
    Information Needs of Gravel Road Stakeholders2022In: Infrastructures, E-ISSN 2412-3811, Vol. 7, no 12, article id 166Article in journal (Refereed)
    Abstract [en]

    Within any ecosystem, information sharing is essential. In this paper, the Swedish gravel road ecosystem is studied, where information plays a crucial role for the effective management of operations and maintenance. However, efficient information sharing is not enabled due to the lack of appropriate information systems. For addressing this issue, this paper intends to elicit information needs of gravel road stakeholders to support the design of a cloud-based information system. The main purpose is to explore the information needs of stakeholders within the Swedish gravel road ecosystem. Data were collected through in-depth semi-structured interviews with 11 participants representing key stakeholders in the ecosystem. Template analysis was used for analyzing the interview results. The major findings were a set of information needs covering road identification and condition, weather conditions, accessibility and traffic, maintenance policy, and sensor data. The results form a comprehensive information model for the further development of a cloud-based gravel road management system that would contribute to increased traffic safety and comfort, lower maintenance and management costs, and better decision-making abilities.

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  • 2.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Nonparametric structural damage detection algorithm for ambient vibration response: utilizing artificial neural networks and self-organizing maps2016In: Journal of Architectural Engineering, ISSN 1076-0431, E-ISSN 1943-5568, Vol. 22, no 2Article in journal (Refereed)
    Abstract [en]

    This study presentes a new nonparametric structural damage detection algorithm that integrates self-organizing maps with a pattern-recognition neural network to quantify and locate structural damage. In this algorithm, self-organizing maps are used to extract a number of damage indices from the ambient vibration response of the monitored structure. The presented study is unique because it demonstrates the development of a nonparametric vibration-based damage detection algorithm that utilizes self-organizing maps to extract meaningful damage indices from ambient vibration signals in the time domain. The ability of the algorithm to identify damage was demonstrated analytically using a finite-element model of a hot-rolled steel grid structure. The algorithm successfully located the structural damage under several damage cases, including damage resulting from local stiffness loss in members and damage resulting from changes in boundary conditions. A sensitivity study was also conducted to evaluate the effects of noise on the computed damage indices. The algorithm was proved to be successful even when the signals are noise-contaminated.

  • 3.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Do, Ngoan Tien
    University of Alberta, Canada.
    Gul, Mustafa
    University of Alberta, Canada.
    Celik, Ozan
    University of Central Florida, USA.
    Catbas, Necati
    University of Central Florida, USA.
    Quantification of Structural Damage with Self-Organizing Maps2016In: Structural Health Monitoring, Damage Detection & Mechatronics: Proceedings of the 34th IMAC, A Conference and Exposition on Structural Dynamics 2016, Springer, 2016, Vol. 7, p. 47-57Conference paper (Other academic)
    Abstract [en]

    One of the main tasks in structural health monitoring process is to create reliable algorithms that are capable of translating the measured response into meaningful information reflecting the actual condition of the monitored structure. The authors have recently introduced a novel unsupervised vibration-based damage detection algorithm that utilizes self-organizing maps to quantify structural damage and assess the overall condition of structures. Previously, this algorithm had been tested using the experimental data of Phase II Experimental Benchmark Problem of Structural Health Monitoring, introduced by the IASC (International Association for Structural Control) and ASCE (American Society of Civil Engineers). In this paper, the ability of this algorithm to quantify structural damage is tested analytically using an experimentally validated finite element model of a laboratory structure constructed at Qatar University.

  • 4.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Inman, Daniel
    University of Michigan, USA.
    Active vibration control of flexible cantilever plates using piezoelectric materials and artificial neural networks2016In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 363, p. 33-53Article in journal (Refereed)
    Abstract [en]

    The study presented in this paper introduces a new intelligent methodology to mitigate the vibration response of flexible cantilever plates. The use of the piezoelectric sensor/actuator pairs for active control of plates is discussed. An intelligent neural network based controller is designed to control the optimal voltage applied on the piezoelectric patches. The control technique utilizes a neurocontroller along with a Kalman Filter to compute the appropriate actuator command. The neurocontroller is trained based on an algorithm that incorporates a set of emulator neural networks which are also trained to predict the future response of the cantilever plate. Then, the neurocontroller is evaluated by comparing the uncontrolled and controlled responses under several types of dynamic excitations. It is observed that the neurocontroller reduced the vibration response of the flexible cantilever plate significantly; the results demonstrated the success and robustness of the neurocontroller independent of the type and distribution of the excitation force.

  • 5.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Inman, Daniel
    University of Michigan, USA.
    Genetic algorithm use for internally resonating lattice optimization: case of a beam-like metastructure2016In: Dynamics of Civil Structures: Proceedings of the 34th IMAC, A Conference and Exposition on Structural Dynamics 2016 / [ed] Shamim Pakzad, Caicedo Juan, Springer, 2016, p. 289-295Conference paper (Other academic)
    Abstract [en]

    Metamaterial inspired structures, or metastructures, are structural members that incorporate periodic or non-periodic inserts. Recently, a new class of metastructures has been introduced which feature chiral lattice inserts. It was found that this type of inserts has frequency bandgaps which can be tuned by altering the geometry of the chiral lattice. Previous studies have shown that inserting non-periodic chiral lattices inside a beam-like structure results in efficient vibration attenuation at low frequencies. In the study presented in this paper, a genetic algorithm based optimization technique is developed to automatically generate chiral lattices which are tuned to suppress vibration in a flexible beam-like structure. Several parameters are incorporated in the optimization process such as the radius of circular nodes and characteristic angle as well as the spacing and distribution of circular inserts. The efficiency of the …

  • 6.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Inman, Daniel
    University of Michigan, USA.
    Optimization of chiral lattice based metastructures for broadband vibration suppression using genetic algorithms2016In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 369, p. 50-62Article in journal (Refereed)
    Abstract [en]

    One of the major challenges in civil, mechanical, and aerospace engineering is to develop vibration suppression systems with high efficiency and low cost. Recent studies have shown that high damping performance at broadband frequencies can be achieved by incorporating periodic inserts with tunable dynamic properties as internal resonators in structural systems. Structures featuring these kinds of inserts are referred to as metamaterials inspired structures or metastructures. Chiral lattice inserts exhibit unique characteristics such as frequency bandgaps which can be tuned by varying the parameters that define the lattice topology. Recent analytical and experimental investigations have shown that broadband vibration attenuation can be achieved by including chiral lattices as internal resonators in beam-like structures. However, these studies have suggested that the performance of chiral lattice inserts can be maximized by utilizing an efficient optimization technique to obtain the optimal topology of the inserted lattice. In this study, an automated optimization procedure based on a genetic algorithm is applied to obtain the optimal set of parameters that will result in chiral lattice inserts tuned properly to reduce the global vibration levels of a finite-sized beam. Genetic algorithms are considered in this study due to their capability of dealing with complex and insufficiently understood optimization problems. In the optimization process, the basic parameters that govern the geometry of periodic chiral lattices including the number of circular nodes, the thickness of the ligaments, and the characteristic angle are considered. Additionally, a new set of parameters is introduced to enable the optimization process to explore non-periodic chiral designs. Numerical simulations are carried out to demonstrate the efficiency of the optimization process.

  • 7.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Kiranyaz, Serkan
    Qatar University, Qatar.
    Boashash, Boualem
    Qatar University, Qatar; The University of Queensland, Herston, Australia.
    Sodano, Henry
    University of Michigan, USA.
    Inman, Daniel
    University of Michigan, USA.
    1-D CNNs for structural damage detection: verification on a structural health monitoring benchmark data2018In: Neurocomputing, ISSN 0925-2312, E-ISSN 1872-8286, Vol. 275, p. 1308-1317Article in journal (Refereed)
    Abstract [en]

    Structural damage detection has been an interdisciplinary area of interest for various engineering fields. While the available damage detection methods have been in the process of adapting machine learning concepts, most machine learning based methods extract “hand-crafted” features which are fixed and manually selected in advance. Their performance varies significantly among various patterns of data depending on the particular structure under analysis. Convolutional neural networks (CNNs), on the other hand, can fuse and simultaneously optimize two major sets of an assessment task (feature extraction and classification) into a single learning block during the training phase. This ability not only provides an improved classification performance but also yields a superior computational efficiency. 1D CNNs have recently achieved state-of-the-art performance in vibration-based structural damage detection; however, it has been reported that the training of the CNNs requires significant amount of measurements especially in large structures. In order to overcome this limitation, this paper presents an enhanced CNN-based approach that requires only two measurement sets regardless of the size of the structure. This approach is verified using the experimental data of the Phase II benchmark problem of structural health monitoring which had been introduced by IASC-ASCE Structural Health Monitoring Task Group. As a result, it is shown that the enhanced CNN-based approach successfully estimated the actual amount of damage for the nine damage scenarios of the benchmark study.

  • 8.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Kiranyaz, Serkan
    Qatar University, Qatar.
    Gabbouj, Moncef
    Tampere University of Technology, Finland.
    Inman, Daniel
    University of Michigan, USA.
    Real-time vibration-based structural damage detection using one-dimensional convolutional neural networks2017In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 388, p. 154-170Article in journal (Refereed)
    Abstract [en]

    Structural health monitoring (SHM) and vibration-based structural damage detection have been a continuous interest for civil, mechanical and aerospace engineers over the decades. Early and meticulous damage detection has always been one of the principal objectives of SHM applications. The performance of a classical damage detection system predominantly depends on the choice of the features and the classifier. While the fixed and hand-crafted features may either be a sub-optimal choice for a particular structure or fail to achieve the same level of performance on another structure, they usually require a large computation power which may hinder their usage for real-time structural damage detection. This paper presents a novel, fast and accurate structural damage detection system using 1D Convolutional Neural Networks (CNNs) that has an inherent adaptive design to fuse both feature extraction and classification blocks into a single and compact learning body. The proposed method performs vibration-based damage detection and localization of the damage in real-time. The advantage of this approach is its ability to extract optimal damage-sensitive features automatically from the raw acceleration signals. Large-scale experiments conducted on a grandstand simulator revealed an outstanding performance and verified the computational efficiency of the proposed real-time damage detection method.

  • 9.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Kiranyaz, Serkan
    Qatar University, Qatar.
    Inman, Daniel
    University of Michigan, USA.
    Optimization of linear zigzag insert metastructures for low-frequency vibration attenuation using genetic algorithms2017In: Mechanical systems and signal processing, ISSN 0888-3270, E-ISSN 1096-1216, Vol. 84, no Part A, p. 625-641Article in journal (Refereed)
    Abstract [en]

    Vibration suppression remains a crucial issue in the design of structures and machines. Recent studies have shown that with the use of metamaterial inspired structures (or metastructures), considerable vibration attenuation can be achieved. Optimization of the internal geometry of metastructures maximizes the suppression performance. Zigzag inserts have been reported to be efficient for vibration attenuation. It has also been reported that the geometric parameters of the inserts affect the vibration suppression performance in a complex manner. In an attempt to find out the most efficient parameters, an optimization study has been conducted on the linear zigzag inserts and is presented here. The research reported in this paper aims at developing an automated method for determining the geometry of zigzag inserts through optimization. This genetic algorithm based optimization process searches for optimal zigzag designs which are properly tuned to suppress vibrations when inserted in a specific host structure (cantilever beam). The inserts adopted in this study consist of a cantilever zigzag structure with a mass attached to its unsupported tip. Numerical simulations are carried out to demonstrate the efficiency of the proposed zigzag optimization approach.

  • 10.
    Abdeljaber, Osama
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Dorn, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Brandt, Anders
    University of Southern Denmark, Denmark.
    Scaling an OMA Modal Model of a Wood Building Using OMAH and a Small Shaker2020In: Topics in Modal Analysis & Testing: Volyme 8 / [ed] Dilworth B., Mains M., Springer, 2020, p. 151-157Conference paper (Refereed)
    Abstract [en]

    Operational modal analysis, OMA, results in unscaled mode shapes, since no forces are measured. Yet, obtaining a scaled modal model, i.e. knowing the modal mass of each mode (assuming proportional damping), is essential in many cases for structural health monitoring and load estimation. Several methods have therefore recently been developed for this purpose. The so-called OMAH method is a recently developed method for scaling OMA models, based on harmonic excitation of the structure. A number of frequencies are excited, one by one, and for each frequency, one or more frequency response values are calculated, that are then used for estimation of the modal masses of each mode, and residual effects of modes outside the frequency of interest. In the present paper, measurements were made on a four-story office building which was excited with a small, 200 N sine peak electrodynamic shaker. It is demonstrated that this small shaker was sufficient to excite the building with a force level of approx.. 1.8 N RMS close to the first eigenfrequency of the building, which was sufficient to produce harmonic response across the building. Reliable modal masses were possible to obtain within an accuracy of 6%. This demonstrates the feasibility of the OMAH method.

  • 11.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Hussein, Mohammed
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Davis, Brad
    University of Kentucky, USA.
    Reynolds, Paul
    University of Exeter, UK.
    A novel video-vibration monitoring system for walking pattern identification on floors2020In: Advances in Engineering Software, ISSN 0965-9978, E-ISSN 1873-5339, Vol. 139, article id 102710Article in journal (Refereed)
    Abstract [en]

    Walking-induced loads on office floors can generate unwanted vibrations. The current multi-person loading models are limited since they do not take into account nondeterministic factors such as pacing rates, walking paths, obstacles in walking paths, busyness of floors, stride lengths, and interactions among the occupants. This study proposes a novel video-vibration monitoring system to investigate the complex human walking patterns on floors. The system is capable of capturing occupant movements on the floor with cameras, and extracting walking trajectories using image processing techniques. To demonstrate its capabilities, the system was installed on a real office floor and resulting trajectories were statistically analyzed to identify the actual walking patterns, paths, pacing rates, and busyness of the floor with respect to time. The correlation between the vibration levels measured by the wireless sensors and the trajectories extracted from the video recordings were also investigated. The results showed that the proposed video-vibration monitoring system has strong potential to be used in training data-driven crowd models, which can be used in future studies to generate realistic multi-person loading scenarios.

  • 12.
    Abdeljaber, Osama
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology. Qatar University, Qatar.
    Younis, Adel
    Qatar University, Qatar.
    Alhajyaseen, Wael
    Qatar University, Qatar.
    Analysis of the Trajectories of Left-turning Vehicles at Signalized Intersections2020In: Recent Advances and Emerging Issues in Transport Research / [ed] Fusun ULENGİN, Gopal R. PATIL, Ozay OZAYDIN, Lóránt TAVASSZY, Ashish VERMA, Elsevier, 2020, p. 1288-1295Conference paper (Refereed)
    Abstract [en]

    Internationally, an annual number of more than a million fatalities are caused by road traffic crashes, with particularly signalized intersections being crash prone locations within the highway system. An accumulation of conflicts between drivers is caused by the  different  movements  (through  and  turning)  from  different  directions  at  the  intersection;  hence,  studying  the  trajectories  of  turning vehicles is an important step towards improving traffic safety performance of these facilities. In view of that, the current paper aims at providing further insight into the behaviour of left-turning vehicles (right-hand traffic rule) at signalized intersections in the State of Qatar. At first, a total of 44 trajectories of free-flowing vehicles were manually extracted from a recorded video for a  single  approach  of  Lekhwair  signalized  intersection  in  Doha  City,  State  of  Qatar.  After  that,  the  extracted  trajectories  were statistically analysed in an attempt to explore the factors affecting the path of left-turning vehicles at signalized intersections. The results suggest that the characteristics of the extracted paths are significantly related to the vehicle’s entry speed, minimum speed throughout its turning manoeuvre, and the lateral distance between the exit point and the curb (i.e., targeted exit lane). Provided that the speed parameters can be fairly an indication to the driving behaviour, it can be concluded that the driver’s attitude plays an important role in drawing the manoeuvre of a turning vehicle as does the pre-selection of the exit lane. Finally, the effort presented in this paper can be regarded as a way forward towards understanding the behaviour of turning vehicles at signalised intersection in the State of Qatar.

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  • 13.
    Abdeljaber, Osama
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Younis, Adel
    Qatar University, Qatar.
    Alhajyaseen, Wael
    Qatar University, Qatar.
    Extraction of Vehicle Turning Trajectories at Signalized Intersections Using Convolutional Neural Networks2020In: Arabian Journal for Science and Engineering, ISSN 2193-567X, Vol. 45, p. 8011-8025Article in journal (Refereed)
    Abstract [en]

    This paper aims at developing a convolutional neural network (CNN)-based tool that can automatically detect the left-turning vehicles (right-hand traffic rule) at signalized intersections and extract their trajectories from a recorded video. The proposed tool uses a region-based CNN trained over a limited number of video frames to detect moving vehicles. Kalman filters are then used to track the detected vehicles and extract their trajectories. The proposed tool achieved an acceptable accuracy level when verified against the manually extracted trajectories, with an average error of 16.5 cm. Furthermore, the trajectories extracted using the proposed vehicle tracking method were used to demonstrate the applicability of the minimum-jerk principle to reproduce variations in the vehicles’ paths. The effort presented in this paper can be regarded as a way forward toward maximizing the potential use of deep learning in traffic safety applications.

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  • 14.
    Abdeljaber, Osama
    et al.
    Qatar University, Qatar.
    Younis, Adel
    Qatar University, Qatar.
    Avci, Onur
    Qatar University, Qatar.
    Catbas, Necati
    University of Central Florida, USA.
    Gul, Mustafa
    University of Central Florida, USA.
    Celik, Ozan
    University of Central Florida, USA.
    Zhang, Haiyang
    University of Alberta, USA.
    Dynamic Testing of a Laboratory Stadium Structure2016In: Geotechnical and Structural Engineering Congress 2016, American Society of Civil Engineers (ASCE), 2016, p. 1719-1728Conference paper (Other academic)
    Abstract [en]

    Studies with large physical models are a vital link between the theoretical work and field applications provided that these models are designed to represent real structures where various types and levels of uncertainties can be incorporated. While comprehensive analytical and laboratory joint studies are ongoing at Qatar University, University of Central Florida and University of Alberta, this paper presents the initial findings of dynamic testing at Qatar University. A laboratory stadium structure (grandstand simulator) has been constructed at Qatar University. Capable of housing thirty spectators, Qatar University grandstand simulator is arguably the largest laboratory stadium in the world. The structure is designed in a way that several different structural configurations can be tested in laboratory conditions to enable researchers to test newly developed damage detection algorithms. The study presented in this paper covers the finite element modeling and modal testing of the test structure.

  • 15.
    Abdula, Sham
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Oksman, Dan
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Attefallshus som komplementbostadshus: Drömhus eller mardröm?2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Den 2 juli 2014 blev det enligt lag tillåtet för en- och tvåbostadshusägare att uppföra en bygglovsbefriad komplementbyggnad på max 25 kvadratmeter på den egna fastigheten. Rapporten undersöker vilket genomslag lagändringen har haft i Stor-Stockholm, Stor-Göteborg och Stor-Malmö. Undersökningen visar att lagändringen ännu inte har haft något stort genomslag. I rapporten undersöks även en utvald del av marknadsaktörers utbud av attefallshus avsett som komplementbostadshus. 

    Ett attefallshus utformas med miljövänligt hållbara material och inspireras av Vitruvius tre principer för god arkitektur. Huset konstrueras med avsikt att uppfylla kraven som ställs i PBL, PBF, BBR och EKS. Målet med de framtagna bygghandlingarna är att få startbesked från byggnadsnämnden i Växjö. 

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  • 16.
    Abdulhadi, Ahmed
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Brånemo, Oskar
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Jämförelse av betongkonstruktioner som dimensionerats under olika svenska byggnormer2023Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In the construction sector today, there is a lot of discussion about material reuse tominimize the negative environmental impact. By reuse of precast concreteelements, significant amounts of CO2 emissions can be prevented. In order toreuse a concrete element for structural purposes in a building, the element need tobe assessed to ensure it can withstand the required loads.

    This report is based on a comparison of different building codes, it describes andcompares three selected building codes and their associated concrete standardsfrom different eras. The purpose of the report is to compare the results obtainedwhen designing predetermined concrete elements and components. The findingswill indicate whether it is possible to reuse concrete elements that were designedaccording to previous standards. The calculations will demonstrate bothsimilarities and, more importantly, differences in the design approaches of thebuilding codes and how they have evolved.

    An investigation concludes that by employing a chain of checks, it is possible todetermine if an existing component is reusable considering its load capacity.

    The differences in reinforcement content vary within approximately 0-25% infavor of the previous code, i.e. the older code requires more reinforcement.

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  • 17.
    Abrahamsen, Rune
    et al.
    Moelven Limtre, Norway.
    Bjertnaes, Magne A.
    Sweco, Norway.
    Bouillot, Jacques
    Eiffage, France.
    Brank, Bostjan
    University of Ljubljana, Slovenia.
    Cabaton, Lionel
    Arbonis, France.
    Crocetti, Roberto
    Moelven, Sweden.
    Flamand, Olivier
    CSTB, France.
    Garains, Fabien
    Eiffage, France.
    Gavric, Igor
    InnoRenew, Slovenia.
    Germain, Olivier
    Galeo, France.
    Hahusseau, Ludwig
    Eiffage, France.
    Hameury, Stephane
    CSTB, France.
    Johansson, Marie
    RISE, Sweden.
    Johansson, Thomas
    Moelven, Sweden.
    Ao, Wai Kei
    University of Exeter, UK.
    Kurent, Blaz
    University of Ljubljana, Slovenia.
    Landel, Pierre
    RISE, Sweden.
    Linderholt, Andreas
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering. Linnaeus University, Linnaeus Knowledge Environments, Advanced Materials.
    Malo, Kjell
    NTNU Norwegian University of Science and Technology, Norway.
    Manthey, Manuel
    CSTB, France.
    Nåvik, Petter
    Sweco, Norway.
    Pavic, Alex
    University of Exeter, UK.
    Perez, Fernando
    Smith and Wallwork, UK.
    Rönnquist, Anders
    NTNU Norwegian University of Science and Technology, Norway.
    Stamatopoulos, Haris
    NTNU Norwegian University of Science and Technology, Norway.
    Sustersic, Iztok
    InnoRenew, Slovenia.
    Tulebekova, Salue
    NTNU Norwegian University of Science and Technology, Norway.
    Dynamic Response of Tall Timber Buildings Under Service Load: The DynaTTB Research Program2020In: EURODYN 2020, XI international conferece on structural dynamics: Proceedings, Volym II / [ed] M. Papadrakakis, M. Fragiadakis, C. Papadimitriou, National Technical University of Athens , 2020, p. 4900-4910Conference paper (Refereed)
    Abstract [en]

    Wind-induced dynamic excitation is becoming a governing design action determin-ing size and shape of modern Tall Timber Buildings (TTBs). The wind actions generate dynamic loading, causing discomfort or annoyance for occupants due to the perceived horizontal sway – i.e. vibration serviceability failure. Although some TTBs have been instrumented and meas-ured to estimate their key dynamic properties (natural frequencies and damping), no systematic evaluation of dynamic performance pertinent to wind loading has been performed for the new and evolving construction technology used in TTBs. The DynaTTB project, funded by the Forest Value research program, mixes on site measurements on existing buildings excited by heavy shakers, for identification of the structural system, with laboratory identification of building elements mechanical features coupled with numerical modelling of timber structures. The goal is to identify and quantify the causes of vibration energy dissipation in modern TTBs and pro-vide key elements to FE modelers.

    The first building, from a list of 8, was modelled and tested at full scale in December 2019. Some results are presented in this paper. Four other buildings will be modelled and tested in spring 2020.

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  • 18.
    Abrahamsen, Rune
    et al.
    Moelven Limtre, Norway.
    Bjertnæs, Magne A.
    Sweco, Norway.
    Bouillot, Jacques
    Eiffage, France.
    Brank, Boštjan
    University of Ljubljana, Slovenia.
    Crocetti, Roberto
    Moelven SE, Sweden.
    Flamand, Olivier
    CSTB, France.
    Garains, Fabien
    Arbonis, France.
    Gavrić, Igor
    InnoRenew, Slovenia.
    Hahusseau, Ludwig
    Eiffage, France.
    Jalil, Alan
    CSTB, France.
    Johansson, Marie
    RISE, Sweden.
    Johansson, Thomas
    Moelven, Sweden.
    Ao, Wai Kei
    Uni Exeter, UK.
    Kurent, Blaž
    University of Ljubljana, Slovenia.
    Landel, Pierre
    Linnaeus University, Faculty of Technology, Department of Building Technology. Rise, Sweden.
    Linderholt, Andreas
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    Malo, Kjell
    NTNU, Norway.
    Manthey, Manuel
    CSTB, France.
    Nåvik, Petter
    Sweco, Norway.
    Pavic, Alex
    Uni Exeter, UK.
    Perez, Fernando
    Smith&Wallwork, Switzerland.
    Rönnquist, Anders
    NTNU, Norway.
    Šušteršič, Iztok
    InnoRenew, Slovenia.
    Tulebekova, Saule
    NTNU, Norway.
    Dynamic response of tall timber buildings under service load: results from the dynattb research program2023In: World Conference on Timber Engineering 2023 (WCTE 2023): Timber for a Livable Future, 19-22 june, 2023,Oslo, Norway / [ed] Nyrud, A. Q. and Malo, K. A. et al., Curran Associates, Inc., 2023, p. 2907-2914Conference paper (Refereed)
    Abstract [en]

    Wind-induced dynamic excitation is a governing design action determining size and shape of modern Tall Timber Buildings (TTBs). The wind actions generate dynamic loading, causing discomfort or annoyance for occupants due to the perceived horizontal sway, i.e. vibration serviceability problem. Although some TTBs have been instrumented and measured to estimate their key dynamic properties (eigenfrequencies, mode shapes and damping), no systematic evaluation of dynamic performance pertinent to wind loading had been performed for the new and evolving construction technologies used in TTBs. The DynaTTB project, funded by the ForestValue research program, mixed on site measurements on existing buildings excited by mass inertia shakers (forced vibration) and/or the wind loads (ambient vibration), for identification of the structural system, with laboratory identification of building elements mechanical features, coupled with numerical modelling of timber structures. The goal is to identify and quantify the causes of vibration energy dissipation in modern TTBs and provide key elements to finite element models. This paper presents an overview of the results of the project and the proposed Guidelines for design of TTBs in relation to their dynamic properties.

  • 19.
    Abrahamsson, Jenny
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    la Fleur, Filip
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    The impact of connection stiffness on the global structural behavior in a CLT building: A combined experimental-numerical study2021Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Cross Laminated Timber (CLT) has in recent years become a more important building material. This means that the demand for accurate calculation methods in building standards such as Eurocode 5 has increased. There is limited knowledge about the connections in CLT buildings which is an important part of a CLT structure. This thesis was therefore focused on investigating a wall-floor-wall type connection commonly found in platform type buildings. 

    An experimental and numerical study on typical wall-floor-wall connections was carried out in this thesis. In the experimental part 60 tests with 8 different configurations were conducted to investigate the influence of different parameters on the connection, moment capacity and rotational stiffness. During the tests the deformation of the specimens under four load levels were investigated. Compression tests were also performed on the specimens to determine the compressive strength and stiffness of the elements. In the numerical part two different models for the connection were created. One simplified model with rotational springs and one more complex model with compression springs. With these models the influence from the number of stories, span and thickness of the wall on the global behavior of a structure was investigated. 

    The result from this thesis shows that there is both moment capacity and rotational stiffness in the wall-floor-wall type connection that can be utilized in the design phase of a structure. This was proven by both the experimental and the numerical study. The parameters that influence the behavior of the connection most were the load level applied on the wall and the wall thickness. The model created in the numerical study showed great potential regarding the replication of the connection behavior observed in the experimental study.  

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  • 20.
    Addassi, Mouadh
    et al.
    Technical University of Denmark, Denmark.
    Johannesson, Björn
    Linnaeus University, Faculty of Technology, Department of Building Technology. Linnaeus University, Linnaeus Knowledge Environments, Advanced Materials.
    Reactive mass transport in concrete including for gaseous constituents using a two-phase moisture transport approach2020In: Construction and Building Materials, ISSN 0950-0618, E-ISSN 1879-0526, Vol. 232, p. 1-14, article id 117148Article in journal (Refereed)
    Abstract [en]

    This article presents the further development of a tool for multi-phase reactive mass transport modelingfor durability estimation of cement-based materials, by the addition of the gas phase, adopting a trulyseparate two-phase moisture transport approach. The governing system of equations are based on phys-ically sound hybrid mixture based version of the Poisson-Nernst-Planck system of equations includinggaseous transport in the air-filled space, ionic transport in the liquid phase, electro-migration of ionicspecies, a two-phase moisture transport model, and sorption. The addition of the gas phase and thetwo-phase moisture description enables the user of the model to investigate individual and combinedeffects of different degradation processes in unsaturated systems. The altering of hydrated cement underthree different environments were studied representing an accelerated carbonation environment, a sub-merged marine environment and a cyclic drying-wetting zone in a marine environment, to illustratesome of the model’s capabilities.

  • 21.
    Addassi, Mouadh
    et al.
    Technical University of Denmark, Denmark.
    Johannesson, Björn
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Wadsö, Lars
    Lund University, Sweden.
    Inverse analyses of effective diffusion parameters relevant for a two-phase moisture model of cementitious materials2018In: Cement and Concrete Research, ISSN 0008-8846, E-ISSN 1873-3948, Vol. 106, p. 117-129Article in journal (Refereed)
    Abstract [en]

    Here we present an inverse analyses approach to determining the two-phase moisture transport properties re-levant to concrete durability modeling. The purposed moisture transport model was based on a continuumapproach with two truly separate equations for the liquid and gas phase being connected by the sorption ki-netics. The moisture properties of ten binder-systems containingfly ash, calcined clay, burnt shale and graymicro-filler, were investigated experimentally. The experiments used were, (i) sorption test (moisturefixation),(ii) cup test in two different relative humidity intervals, (iii) drying test, and, (iv) capillary suction test. Masschange over time, as obtained from the drying test, the two different cup test intervals and the capillary suctiontest, was used to obtain the effective diffusion parameters using the proposed inverse analyses approach. Themoisture properties obtained with the proposed inverse analyses method provide a good description of the testperiod for the ten different binder-systems.

  • 22.
    Ahaki Lakeh, Amir
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Tahmasbi, Milad
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Life cycle assessment and structural analysis of renovation of Ulriksberg school building in Växjö2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Massive volumes of hazardous emissions have been produced by the construction sector for which some adequate steps are implemented, but the rising trend of emissions can still be seen. In this thesis, the goal is to identify and analyze renovation measures from primary energy use and environmental impacts perspective, according to Boverket’s mandatory provisions and general recommendations (BBR 2018), for an old school building. Also, as a part of the study goal, the building structure is analyzed under the updated Eurocode SS-EN 90-91-96 in order to see if the building meets structural stability requirements. Life cycle assessment of the building is limited to production and construction stages, and it is used as a tool to evaluate the environmental impacts according to standard SS-EN 15978:2011. Most of the relevant data are provided by VÖFAB, in cooperation with Växjö municipality, as well as the company WSP group.

    The object of the thesis is an old three-story school building constructed in 1950 in Växjö, Sweden. The gross area of the building is 1,300 m2 and for renovation scenarios, building envelope components are investigated by adding new insulation materials considering two life cycle stages. In the production phase, the lowest primary energy use was 137 kWh/m2 for the scenario of using cellulose insulation material plus windows and exterior doors with a U-value of 1.1 [W/m2 K]. The lowest environmental impacts were also obtained for this scenario, with 14 kg CO2-eq/m2 global warming potential (GWP), 0.06 kg SO2-eq/m2 acidification potential (AP), and 0.06 kg NO3-eq/m2 eutrophication potential (EP). The results indicate that the share of the installation step in the primary energy use and environmental impacts during the construction phase is negligible, but the transportation role in this stage is significant. The highest global warming potential is for the scenario using cellulose insulation material plus windows and exterior doors with a U-value of 0.7 [W/m2 K] with 4.4 kg CO2-eq/m2 in the construction stage. Ultimately, the material production stage accounts for the most share of primary energy use and environmental impacts. 

    This research provides several renovation measures investigated by life cycle assessment resulting in performing climate declarations. Regarding the sensitivity analysis, the electricity source has a considerable effect on reducing total primary energy consumption and environmental impacts during the production phase. It is also found that the scenario utilizing cellulose insulation material with windows with a U-value of 1.1 [W/m2 K] shows the lowest total primary energy use and environmental impacts. Through analyzing the building structure, all Eurocode criteria within the serviceability limit state (SLS) and ultimate limit state (ULS) are fulfilled, and the structure is still stable when new materials are added through renovation.

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  • 23.
    Ahlgren, Sara
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Lindström, Jenny
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Ekonomi, kunskap och kommunikation: – Avgörande för den estetiska kvaliteten vid nyproduktion av bostäder2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There are indications that the architecture in Sweden is perceived as more and more monotonous with the absence of aesthetic qualities. Architects are allowed to bear responsibility for the claim but they themselves believe that they deprived their position in the construction process where they are replaced under ongoing projects, ancillary financial interests.

    The goal of the work was to find out what happens to a building's aesthetic qualities when the architect is replaced and what lies behind the replacement of the architect. A comparison of two objects was made, one in which the architect has been involved throughout the process and one where the architect has been replaced. The study was conducted through fact-finding from literature, observations and interviews.

    The result shows that the desire to build beautifully with aesthetic qualities is strongly linked to the client's level of ambition. However, the overall result shows that aesthetic values are subordinated to the economy of the construction-process. Furthermore, it has emerged during the work with this essay that there is a lack of knowledge and difficulties in communication between the actors in the construction industry, especially between architects and contractors. 

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  • 24.
    Ahlström, Julia
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Leman, Sandra
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Vägen till ett attraktivare samhälle med ödehus som resurs: Ett gestaltningsförslag för Skruv2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In Sweden there are large differences between living in the city and the countryside. To make the countryside more attractive as a place of living, improvement is necessary in some regions. One such region is Skruv, a village that consists of a lot of deserted houses. 

    The purpose of the study is to improve the living conditions in this region. As a result, a design proposal has been created.

    In the creation of this study, both information gathered from field studies and interviews with subject relevant professionals has acted as a basis. This all surmised into a proposal with the old stationhouse as a central role. The proposal has a futuristic angle, as it expects there to be a functioning train stop, something which also increase the attractiveness of the region. In the proposal the chosen deserted houses consist of functions that are deemed desired by the inhabitants in Skruv. 

    Overall functions in a society are the same regardless of the geographical location. It’s important to look at a place specific conditions and resources to enable a favorable development.

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  • 25.
    Ahmad, Elaf
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Hultgren, Mathilda
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Möjligheter för visualisering i presentation av småhus2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Rapporten behandlar hur husleverantörer kan utveckla presentationsmaterial. De materialen som visas är olika husmodeller från företagen och behandlar bakgrundsvyer samt förbättringar i digital media. Företaget som ligger till grund för rapporten är Trivselhus, och undersökningarna i rapporten är baserade på aktörer i anknytning till företaget. Resultatet kan även tillämpas hos andra husleverantörer.

    Visualisering handlar om hur människan tar till sig den informationen som ges. Den används för att underlätta förståelsen för komplicerade bilder och idéer som visas för kunder. Visualisering möjliggör att bearbetade bilder kan kopplas samman med slutresultatet som presenteras.

    Informationen som kommer genom visualisering kan fås genom människans fem sinnen syn, lukt, hörsel, smak och känsel. Denna studie lägger fokus på den synliga aspekten till visualisering och hur företag kan använda den för att förstärka sin kundkrets.

    Resultatet ger exempel på visualisering som husleverantörer kan tillämpa i verksamheten. Det behandlar bland annat utveckling av hemsidor och gemensamma plattformar som kund och säljare båda kan arbeta i. Andra framtidsförslag som presenteras är en utveckling av visningshus samt producering av miniatyrhus. Detta för att ge kunden en bättre visualisering och därmed en större insyn i hur det färdiga huset är utformat och kommer fungera i verkligheten.

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  • 26.
    Ahn, Namhyuck
    et al.
    Oregon State University, USA.
    Bjarvin, Christina
    University of Washington, USA.
    Riggio, Mariapaola
    Oregon State University, USA.
    Muszynski, Lech
    Oregon State University, USA.
    Schimleck, Laurence
    Oregon State University, USA.
    Pestana, Catarina
    Oregon State University, USA.
    Dodoo, Ambrose
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Puettmann, Maureen
    WoodLife Environmental Consultants, USA.
    Envisioning mass timber buildings for circularity: life cycle assessment of a mass timber building with different end-of-life (EoL) and post-EoL options2023In: WCTE 2023-World Conference on Timber Engineering: Timber for a Livable Future, 19-22 June, Oslo. 2898-2906 / [ed] Nyrud, A. Q. and Malo, K. A. et al., Curran Associates, Inc., 2023, p. 3581-3587Conference paper (Refereed)
    Abstract [en]

    The foundation of the circular economy in the construction sector is based on implementing the deconstruction and reuse of buildings, providing the potential for a closed loop of building materials within the supply chain. Mass timber buildings using large, prefabricated elements and certain types of reversible mechanical connections are deemed to have great potential for post end-of-life (EoL) options, including recycling and reuse. To fully characterize the benefits of reusing post-use mass timber in new construction projects, it is crucial to conceptualize a ‘grave-to-gate’ approach, including the complete analysis of post-EoL activities and impacts on the material’s second life. In this study, a comparative life cycle assessment (LCA) including different EoL and post-EoL options for a virtual reference mid-rise mass timber building in the Pacific Northwest (PNW) of the United States was conducted. Among four different deconstruction and reuse scenarios examined in this study, a case of nearly complete reconstruction of a mass timber building for the second service life used as an idealized reference established an optimistic limit for reduction of global warming potential (GWP) by 13-41% compared to the ‘demolish and landfill’ decision, depending on the scenario. The demolition and landfill scenario had the lowest net impact since the GWMP calculations accounted for the carbon storage benefits in the landfill in addition to the carbon stored in the building.

  • 27.
    Ahn, Namhyuck
    et al.
    College of Forestry, USA.
    Dodoo, Ambrose
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Riggio, Mariapaola
    College of Forestry, USA.
    Muszynski, Lech
    College of Forestry, USA.
    Schimleck, Laurence
    College of Forestry, USA.
    Puettmann, Maureen
    WoodLife Environmental Consultants, USA.
    Circular economy in mass timber construction: State-of-the-art, gaps and pressing research needs2022In: Journal of Building Engineering, E-ISSN 2352-7102, Vol. 53, article id 104562Article in journal (Refereed)
    Abstract [en]

    The building and construction sector is a major contributor to human environmental impact on the planet. It follows that the sector's contribution is also crucial for transition towards a low carbon society and circular economy (CE). Mass timber products, are one of the sustainable alternatives to traditional building materials and have led to the recent revolution in timber construction. While environmental benefits of mas timber manufacturing and construction is well documented the end-of-life (EOL) and the post-EOL options for mass timber buildings, their environmental benefits and CE potential are discussed much less. Short history of construction technology involving prefabricated mass timber panels compared to traditional building types results in virtually no documented cases of panelized mass timber structures reaching the EOL stage and no practical examples of incorporating CE concepts in such projects. In this study, a two-step systematic literature review was used, to define and classify 23 CE-based governing principles from six categories in the construction industry, and to use those principles to analyze the state-of-the-art circular approach in mass timber research. The study covered a total of 90 papers, of which 68 focused on the general construction industry and 22 specifically on the mass timber construction. Results of this review suggest substantial gaps in knowledge and pressing research needs for the development of holistic approaches to prepare the mass timber construction for circular economy.

  • 28.
    Akter, Shaheda T.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Experimental characterization and numerical modeling of compression perpendicular to the grain in wood and cross-laminated timber2022Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Compression perpendicular to the grain (CPG) of wood is a typical loading situation in timber structures. It has been an extensively studied research topic for decades, due to the highly ductile behavior of wood under such loading, the large variations in mechanical properties, and the relevance of these properties in structural design. Among others, the main influencing factors for CPG properties are stressed volume, load and support configurations, and annual ring orientations to the loading direction. After the innovation of the massive, engineered wood based product, cross-laminated timber (CLT) and its application in high rise buildings, CPG of wood has gained further importance. The development of a non-homogeneous, undesired and combined stress state under CPG in solid wood, due to the material anisotropy in the radial-tangential plane, can build up a complex multi-axial stress state in CLT. As a comparatively new product, the study of the influencing factors for CPG properties of CLT, and an understanding of the local material behavior under such loading, is essential for product characterization and for the development of design guidelines to ensure safe and efficient design.

    The main aim of the doctoral thesis is to establish a relationship betweenthe anisotropic behavior of clear wood in the transverse plane and the structural response of CLT under CPG loading. Both experimental and numerical studies were adopted herein, to enhance the understanding of the basic material behavior and the product and structural behavior. On the clear wood scale, the focus was on developing a test setup for uniaxial and biaxial loading in the radial-tangential(RT) plane. The potential of the developed test setup for the biaxial testing in the transverse plane was exploited for the investigation of the moisture and time dependent behavior of clear wood under radial compression and rolling shear loading. For data acquisition, in addition to the force and displacement data measured by the internal actuators of the testing machine and an external load cell,a contact-free digital image correlation (DIC) system was used in the experimental investigations. A numerical model was developed, which can describe the elasto-plastic behavior of wood under compression in the transverse plane and predict the structural behavior of solid wood and CLT. For that purpose, a novel Quadratic multi-surface (QMS) failure criterion and a simplified Hoffman failure criterion were implemented in a user-subroutine in the finite element software Abaqus®, and their suitability was compared with the Abaqus implemented Hill’s criterion.The validation of the material models was based on the experimental investigations of failure behavior of clear wood under stress perpendicular to the grain with rolling shear interaction. The material models were further utilized to predict the structural response of solid wood and CLT wall-to-floor connections under CPG loading. The predicted response of CLT connections under CPG by using the above-mentioned material models was compared with experiments, which investigated the influences of different connection types, wall and floor thicknesses, positions of walls, and outer deck layer orientations. The models were then applied to investigate the influence of the pith location in the boards, the number of layers and the thickness of walls and the floor on the stiffness and strength of CLT connections. Moreover, the CLT connection’s rotational rigidity as a consequence of compressive force from the upper floor in a multi-story building was studied by means of finite element calculations.

    The DIC measured strain fields from the experiments on clear wood confirmed the dependence of strain field on the curvature of the annual rings. As regards the material models, Hill’s model resulted in significantly higher force carrying capacity than experiments on clear wood, whereas Hoffman’s and QMS models predicted reasonably well the force-displacement relationships as found in experiments. The Hoffman’s and QMS models predicted stiffness was about 5–10% higher than corresponding experimental results on clear wood, and about 25% higher for CLT connections. The higher difference in the latter case is due to the difference in material properties of clear wood and structural timber, and the contact behavior between the structural members. The results from CLT wall-to-floor connections revealed a strong influence of loading and supporting configurations, wall thickness and pith locations on their stiffness and strength. A compressive loading on the CLT wall showed a positive effect on the rotational stiffness of CLT wall-to-floor connections, which considerably reduces the CLT floor mid-span deflection in comparison to a simply-supported floor.The thesis work contributes to an enhanced understanding of the anisotropic material behavior of wood in the RT-plane and of its effects on structural timber and CLT under CPG loading. The outcomes of the thesis are beneficial to the product design and standardization of CLT and can be applied in further product development and in optimized structural design.

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  • 29.
    Akter, Shaheda T.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Bader, Thomas K.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Enquist, Bertil
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Failure envelope for interaction of stresses perpendicular to the grain with rolling shear stress in wood2018In: 6th European Conference on Computational Mechanics (ECCM 6), 7th European Conference on Computational Fluid Dynamics (ECFD 7), 11 – 15 June 2018, Glasgow, UK, 2018Conference paper (Refereed)
    Abstract [en]

    The orthotropic material property in combination with ductility in compression, brittleness in shear and tension, very low shear modulus in radial-tangential (RT) plane etc. requires anisotropic stress failure criteria, as well as their evolution with increasing strains. Three- dimensional failure criteria have been proposed for this purpose, but their validation in the RT plane with interaction of rolling shear stresses has attracted less attention. Corresponding stress interactions are however important for modelling of engineered wood-based products under compression perpendicular to the grain when taking into account influence of the annual ring structure.

    The work aims at defining failure envelopes for stresses perpendicular to the grain with rolling shear stress interaction based on experimental investigations performed on Norway spruce. The experimental set-up was realized in a biaxial testing frame and consisted of stiff steel plates to transfer load from the testing machine to wood specimen. Mechanical grips prevented rotation and uplifting of the specimen in case of pure shear and tensile loading, respectively. In addition to conventional linear variable differential transformers, a digital image correlation system was used to measure strain fields on the surface of wood specimens and steel plates. Measurements of dog-bone shaped specimens were carried out along different stress interaction paths by displacement controlled loading.

    The experimental dataset was then compared with commonly used phenomenological failure criteria, namely Tsai-Hill, Tsai-Wu [1], Norris [2] and Hoffman, as well as with regression equations from previous works [3].Experiments revealed that the stress-strain relationship under compression, shear, and biaxial loading differs in radial and tangential directions. None of the three-dimensional stress failure criteria provided good prediction of experiments under compression and rolling shear, but experimental data was closer to the regression equation proposed in [3].

  • 30.
    Akter, Shaheda T.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Bader, Thomas K.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University, Sweden.
    Modeling of wood under combination of normal stresses with rolling shear stress2019In: Presented at CompWood 2019 - International Conference on Computational Methods in Wood Mechanics - from material properties to Timber Structures, Växjö, Sweden, June 17-19, 2019, Växjö, Sweden, 2019Conference paper (Refereed)
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  • 31.
    Akter, Shaheda T.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Bader, Thomas K.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University, Sweden.
    Modelling of wood under compression perpendicular to the grain with rolling shear in cross-laminated timber2019In: Presented at COMPLAS 2019 - XV International Conference on Computational Plasticity: Fundamentals and Applications, Barcelona, Spain, September 3-5, 2019, Barcelona, Spain: European Community on Computional Methods in Applied Sciences (ECCOMAS), 2019Conference paper (Refereed)
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  • 32.
    Akter, Shaheda T.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Bader, Thomas K.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University, Sweden.
    Stiffness of cross-laminated timber (CLT) wall-to-floor-to-wall connections in platform-type structures2021In: World Conference on Timber Engineering 2021, WCTE 2021, Santiago, Chile: World Conference on Timber Engineering, WCTE , 2021, article id WPC0232Conference paper (Refereed)
    Abstract [en]

    Wall-to-floor-to-wall connections are important for the performance of multi-storey, platform-type cross-laminated timber (CLT) structures. Their stiffness properties are studied by means of a numerical model, which was previously validated with experimental data from material testing and CLT connections loaded perpendicular to the grain. In this work, the stiffness of CLT wall-to-floor-to-wall connections is derived and its dependence on the compressive loading in the CLT walls and on wall and floor thicknesses were investigated. The compatibility of the local model with the connection size in structural design models, was investigated by studying the effect of the floor length and the wall height in the numerical model. The results showed that both rotational elastic stiffness and moment capacity of the floor connection increase with increasing compressive force on the CLT wall. However, a moderate decrease in stiffness, but a stronger rotation hardening was found for higher wall pressures, while lower wall pressures yielded an ideal plastic behaviour. The wall thickness showed a higher influence on the connection stiffness and moment capacity than the floor thickness. The influence of the support condition on the deflection of a CLT floor was exemplified. This study includes novel stiffness data for the design of CLT floors in platform type constructions.

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  • 33.
    Akter, Shaheda T.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Binder, Eva
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Bader, Thomas K.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Moisture and short-term time-dependent behavior of Norway spruce clear wood under compression perpendicular to the grain and rolling shear2023In: Wood Material Science & Engineering, ISSN 1748-0272, E-ISSN 1748-0280, Vol. 18, no 2, p. 580-593Article in journal (Refereed)
    Abstract [en]

    Material properties of wood under compression perpendicular to the grain and rolling shear are important for the engineering design of timber structures. This regards the short-term stiffness and strength, their dependence on the moisture content of wood, as well as the time-dependent behavior. Norway spruce clear wood properties in the transverse plane of wood were studied inan experimental campaign exploiting an earlier developed biaxial test setup. The moisture dependence of the stiffness and strength and the short-term time-dependent creep deformations under compression in the radial direction and under rolling shear were characterized. Loading and unloading stiffness, as well as the strength, were determined in quasi-static tests at five different moisture contents from 4% to 29%. The elastic and viscous stiffnesses were identified in creep tests at three compressive stress levels of 0.50, 0.75, and 1.00 N/mm2, and at two rolling shear stress levels of 0.33 and 0.50 N/mm2. The test data complements the existing experimental database, especially with novel data regarding the moisture dependence of the rolling shear strength, which showed less moisture dependence than the compressive strength perpendicular to the grain. The results of the creep tests revealed different material properties for the different loading and material directions of wood.

  • 34.
    Akter, Shaheda T.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Schweigler, Michael
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University, Sweden.
    Bader, Thomas K.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    A Numerical Study of the Stiffness and Strength of Cross-Laminated Timber Wall-to-Floor Connections under Compression Perpendicular to the Grain2021In: Buildings, E-ISSN 2075-5309, Vol. 11, no 10, article id 442Article in journal (Refereed)
    Abstract [en]

    The use of cross-laminated timber (CLT) in multi-story buildings is increasing due to the potential of wood to reduce green house gas emissions and the high load-bearing capacity of CLT. Compression perpendicular to the grain (CPG) in CLT is an important design aspect, especially in multi-storied platform-type CLT buildings, where CPG stress develops in CLT floors due to loads from the roof or from upper floors. Here, CPG of CLT wall-to-floor connections are studied by means of finite element modeling with elasto-plastic material behavior based on a previously validated Quadratic multi-surface (QMS) failure criterion. Model predictions were first compared with experiments on CLT connections, before the model was used in a parameter study, to investigate the influence of wall and floor thicknesses, the annual ring pattern of the boards and the number of layers in the CLT elements. The finite element model agreed well with experimental findings. Connection stiffness was over estimated, while the strength was only slightly under estimated. The parameter study revealed that the wall thickness effect on the stiffness and strength of the connection was strongest for the practically most relevant wall thicknesses between 80 and about 160 mm. It also showed that an increasing floor thickness leads to higher stiffness and strength, due to the load dispersion effect. The increase was found to be stronger for smaller wall thicknesses. The influence of the annual ring orientation, or the pith location, was assessed as well and showed that boards cut closer to the pith yielded lower stiffness and strength. The findings of the parameter study were fitted with regression equations. Finally, a dimensionless ratio of the wall-to-floor thickness was used for deriving regression equations for stiffness and strength, as well as for load and stiffness increase factors, which could be used for the engineering design of CLT connections.

  • 35.
    Akter, Shaheda T.
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Serrano, Erik
    Lund University, Sweden.
    Bader, Thomas K.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Numerical modelling of wood under combined loading of compressionperpendicular to the grain and rolling shear2021In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 244, article id 112800Article in journal (Refereed)
    Abstract [en]

    Numerical modeling is an efficient tool for experimental validation and for gaining a deeper understanding of complex material phenomena, especially when causal relationships are overlaid by material variability. Wood is such a highly orthotropic and complex material, which in engineering problems however is considered as macro- homogeneous. The aim of this study is to numerically investigate stress and strain states of wood in the radial- tangential plane and the influence of the orthotropic material behavior on the structural response. Model vali-dation is based on experiments performed on clear wood of Norway spruce (Picea abies) by using a biaxial test setup. Three material models were used, namely Hill’s plasticity model, the Hoffman criterion and a novel quadratic multi-surface (QMS) criterion. After validation on the local material scale, the models were applied to the engineering problem of compression perpendicular to the grain for studying the effect of the unloaded length. As a novel part, the influence of the annual ring structure on the local material behavior and the global elasto- plastic force–displacement behavior of wood under compression perpendicular to the grain were numerically investigated. Hill’s failure criterion was found to be the least suitable at both length scales, local material behavior and global structural response. The Hoffman and the QMS criteria showed quite good agreement with the biaxial experiments in terms of force–displacement relations and strain distributions for different loading situations, especially for combinations with radial compression, while there was less agreement with experiments for  the  behavior of  combinations with tangential compression. Application of  these material models to compression perpendicular to the grain for studying the unloaded length effect yielded similar trends as observed in structural tests. A reasonable and similar force–displacement response by Hoffman and QMS criteria was observed, while Hill’s model yielded significantly overestimated force carrying capacity. Differences in force-–displacement response for different loading situations were well in line with literature findings and the infl-ence of the annual ring curvature on the overall force–displacement behavior could be quantified.

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  • 36.
    Al Jaafar, Jaafar
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Projektering av platsbyggd villa2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract (in English)

    "This thesis work is a design project of an on-site construcktions. The issue addressed by the project was how to

    devise and design an detached house

    I have examined which architecture-drawings, construcktion-drawings and static calculations are needed to

    produce an on-site construcktions detached house.

    The result is presented in the finished drawings for the construction documents, which show a one-storey

    detached house with an attractive/accessible construction plan. It uses the combination of a strong style of

    architecture and a clear influence of functional design. This is clarified by the bench ceilings, and the facade,

    which is partly laying panel, partly white trimmed.

    Size: 153 square meters

    Number of rooms: 6, where of 3 are bedrooms."

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    FULLTEXT01
  • 37.
    Al Jaafar, Jaafar
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Projektering av platsbyggd villa2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Abstract (in English)

    "This thesis work is a design project of an on-site construcktions. The issue addressed by the project was how to

    devise and design an detached house

    I have examined which architecture-drawings, construcktion-drawings and static calculations are needed to

    produce an on-site construcktions detached house.

    The result is presented in the finished drawings for the construction documents, which show a one-storey

    detached house with an attractive/accessible construction plan. It uses the combination of a strong style of

    architecture and a clear influence of functional design. This is clarified by the bench ceilings, and the facade,

    which is partly laying panel, partly white trimmed.

    Size: 153 square meters

    Number of rooms: 6, where of 3 are bedrooms."

    Download full text (pdf)
    FULLTEXT01
  • 38.
    Alabbasi, Sateh
    et al.
    Qatar University, Qatar.
    Hussein, Mohammed
    Qatar University, Qatar.
    Abdeljaber, Osama
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Avci, Onur
    University of Leeds, UK.
    A numerical and experimental investigation of a special type of floating-slab tracks2020In: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 215, p. 1-16, article id 110734Article in journal (Refereed)
    Abstract [en]

    Floating-Slab Tracks (FST) are predominantly used for mitigating railway-induced vibrations where the concrete slab is mounted on soft resilient bearings to provide vibration isolation. This paper presents a research study on the dynamic behavior of a special type of FST used in the recently built subway system in Doha, Qatar. The special FST has a continuous concrete slab with periodic grooves. Therefore, the track can be modeled as a periodic structure with a slab unit having two elements with different cross-sections. Extensive numerical and experimental investigations were conducted on a multi-unit full-scale mockup track representing the special FST. A fast running model based on the Dynamic Stiffness Method was developed and examined, in an initial numerical exercise, against a detailed Finite Element model for a track with a finite length. In the experimental campaign, a test was performed with an impact hammer to identify the actual vibration response of the mockup track. Results from the experimental investigations were then used for model updating of the fast running model. The model updating process was carried out according to an automated hybrid optimization approach that combines genetic algorithms with a local search method. Finally, the updated model was extended to an infinite model to investigate the influence of varying grooves thickness on the dynamic behavior of the special track with infinite length for both bending and torsion scenarios. The investigations suggested that reducing the thickness below 50% of the full thickness of the slab significantly affects the dynamic behavior of the special FST.

  • 39.
    Al-anbagi, Ali
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Khalil, Dani
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Utformning avlandningsbanors överbyggnad med hänsyn till slitlagrets bärförmåga2020Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [en]

    n this study, the design of the runway structure of the runways is studied in order tocompare different material compositions in the pavement. This is done with the helpof a survey, the program FAARFIELD and peer reviewed studies. Generally, thereare two different types of road structures in an airfield, rigid and flexible (concreteand asphalt). The result obtained shows the difference between the differentdimensions and the material content of the different types of road structures, whenthey are loaded with either heavy or light aircraft models. These results are based ona design period that has been selected for 20 years. In contrast, the stiffness of theconcrete was much higher than the asphalt stiffness, which means that it is better touse concrete in large commercial airports. According to the CDF diagram (thediagram showing whether the structural design conditions are met), the damagecaused by the aircraft is approximately at the same location on the runway for bothsuperstructures, it also means that flexible superstructure maintenance needs to bedone more often, compared to rigid superstructures. The fact that the asphalt has alower modulus of elasticity than the concrete is also a reason why maintenance forflexible superstructures needs to be done more often. However, when the roadstructures became heavily loaded, the total demanding thickness for the rigid roadstructure is calculated to be 760 mm and for the flexible road structure 710 mm.

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  • 40.
    Al-Ansari, Nabil
    et al.
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Te Seng, Meng
    Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design.
    Studentbostäder i trä med Prefab-teknik2009Independent thesis Basic level (degree of Bachelor), 80 credits / 120 HE creditsStudent thesis
    Abstract [en]

    The Results of this thesis was the creation of two designed house variants with a module to

    all the apartments. In addition till the first module there are three other modules of

    apartments that can be put in the houses if it so needs. The house are volume prefabricated

    and are placed on site in a way that it create an enclosure of the area which faces against the

    nature and car parks also lies hidden behind these houses.

    For the actual structure, a cross beam was created to carry the floor above and it is support

    by all four walls. The structure between the first and the second floor has no "syll" but

    instead there are two differently alternative to linking the floors in order so that it will not

    move. The reason with this solution was that there will not be any subsidence when the

    forces from above are pressed down ward. The forces are instead directly down to the next

    timber frame system. This can happen when the real estate's owner might want to build

    more floors on the house than the present two floors house when there is no land to build

    and spaces are needed in the future.

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  • 41.
    Alashker, Basel
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Lindström, Erik
    Karimi, Aziz
    Backaryds kyrka- Bevarande av golvbjälklag2021Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study was carried out in Backaryd’s church following a proposal from Ankdammen konsult. Backaryd’s church was built more than 200 years ago in Ronneby municipality in Blekinge County. Due to changes in heating methods and energy requirements since the church was built, the church today does not meet the energy and comfort requirements of today’s buildings. The study of the Backaryd’s church aims to investigate the floor construction in the church and to find out what factors may be at risk of moisture damage. The study will analyse the church and mainly the condition of the crawl space. In addition, some improvement measures will be proposed to get a comfortable heating inside the church with an appropriate energy use. Both law and society place high requirements on the preservation of valuable and cultural-historical buildings for future generations. In addition, any changes to churches that have been built before 1939 must be approved by the county administrative board.Results from the study show that relative humidity does not reach critical levels either in the crawl space or the church room. There are also no injuries such as mold and rot attacks on the structure. The inventory is of good quality and lacks damage such as cracks and rots.The writers have come up with the following improvement measures:● An annual entertainment of water management systems in crawl space. ● Cover the stone walls with plastic wrap on the inside and make them as dense as possible. ● Place the base of the panty bottom from below up against the floor beam. ● Insulate the floor structure with mineral wool. ● Place a plastic wrap all over the ground in the crawl space. ● install a dehumidifier. 

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    Backaryds kyrka- Bevarande av golvbjälklag
  • 42.
    Albertsen, Henrik
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Lindberg, Amanda
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Lokalt omhändertagande av dagvatten på bostadsfastigheter2016Independent thesis Basic level (professional degree), 180 HE creditsStudent thesis
    Abstract [sv]

    Ett behov finns av att fördröja dagvatten innan det släpps på det kommunala ledningsnätet för att minska flödestopparna och undvika överbelastning. Studien avser att ta fram en förenklad metod för val och utformning av LOD-metod som är anpassad för privata fastighetsägare.

    Ett flertal LOD-anläggningar samt förutsättningar kring dessa har undersökts. Studien har gett en grundläggande information och en beräkningsgång som har förenklats, är lätt att följa och som kan anpassas efter befintliga förutsättningar och önskemål. 

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  • 43.
    Aldarwash, Mustafa
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Bajqinca, Alban
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Nybyggnation av badrum : Jämförelse mellan prefabricerat och platsbyggt ur ett ekonomiskt perspektiv2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med arbetet är att, genom en ekonomisk undersökning skapa underlag som visar vilket alternativ av produktionsmetoderna prefabricerat eller platsbyggt badrum som är att föredra vid en nybyggnation av vårdhem. 

    Resultatet visar att det platsbyggda badrummet ger en ökad totalt kostnad på 627457 kr vilket motsvarar 11,1 procent dyrare än det prefabricerade badrummet. 

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  • 44.
    Aldén, Jonathan
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Pålsson, Kristian
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Robertson, Johan
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Krav och kvalitetssäkring av BIM-objekt inom projektering, produktion samt förvaltning2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Den ökade användningen av BIM har ändrat villkoren inom byggsektorn. Arbetet syftar till att identifiera och definiera de krav och kvalitetssäkringar av BIM-objekt som finns inom projektering, produktion samt förvaltning. Avsaknad av en gemensam standard försvårar kravställning och kvalitetssäkring av BIM-objekt vilket har lett till vissa komplikationer, främst vid konvertering mellan olika programvaror.

    BIM är med sin potential med största sannolikhet en stor del av byggsektorns framtid. För att kunna ta nästa steg i utvecklingen måste en gemensam standard gällande krav och kvalitetssäkring utarbetas.

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  • 45.
    Algabroun, Hatem
    Linnaeus University, Faculty of Technology, Department of Mechanical Engineering.
    On the development of a maintenance approach for factory of the future implementing Industry 4.02017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The objective of this thesis is to develop a maintenance approach that fulfills the requirements of Industry 4.0. It explores the role and importance of maintenance activities in today’s industry. Then, it develops the features and tasks required to be performed by maintenance to fulfill the demands of Industry 4.0. Finally, it develops a reference model to be used in designing maintenance system for Industry 4.0. To perform these studies, real data were collected and applied as well as a typical scenario was implemented.

    The results achieved in the papers of this thesis are 1) a mathematical representation and application of a model that identifies, analyses and prioritizes economic weakness in working areas related to production, 2) a model that analyses, identifies and prioritizes failures that impact the competitive advantages and profitability of companies, 3) characterization of a suitable maintenance technique for Industry 4.0 and 4) a reference model i.e. a framework, that could be utilized to develop a maintenance approach for Industry 4.0.

    The conclusion of this thesis confirms that maintenance has a significant impact on companies’ competitive advantages, other working areas and profitability. To achieve a suitable maintenance technique for Industry 4.0, this technique must be able to monitor, diagnose, prognosis, schedule, assist in execution and present the relevant information. In order to perform these tasks several features must be acquired, the most important features are to be: digitized, automated, intelligent, able to communicate with other systems for data gathering and monitoring, openness, detect deviation in the condition at an early stage, cost- effective, flexible for adding new CM techniques, provide accurate decisions and scalable. The developed framework could be used as a base to design a maintenance system for Industry 4.0. This study contributes to our understanding of the maintenance importance in today’s industry and how to develop a maintenance approach for Industry 4.0.

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    Licentiate Thesis (Comprehensive Summary)
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  • 46.
    Alhadi, Mustafa
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Shehadeh, Zijad
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Guide för beräkning av förband i korslimmade träkonstruktioner: inkl. några dimensioneringsexempel2020Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Cross-laminated timber (CLT) is a rather new construction material that has increased its popularity and usage significantly within the building industry in the past years. In timber buildings, the connections are one of the most challenging parts to design. Thus, there are high demands put on structural engineers to make a safe and economic design. Today structural engineers have no specific and clear guideline that they can use as help for design of connections in CLT-buildings. By reviewing the most common CLT-handbooks, comparing them with each other, and picking out the best parts from each of the handbooks, a new guideline for design of connections in CLT-structures was developed in this thesis with complementary design examples. The guidelines main purpose is to act as help for the structural engineer when designing connections in CLT-structures. It is indented that the guideline acts as basis for the development of a future CLT-handbook with a collection of supporting calculation examples.

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  • 47.
    Alhameedi, Ali
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Hybrid testing procedure development: An experimental study a hybrid simulation of a steel truss element2019Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Hybrid simulation is a numerical and experimental structural testing technique in which the critical structural members are tested experimentally, while the rest of the structure is modeled numerically. During hybrid testing, the numerical model is updated continuously based on the output of the experimental test. In this study, a quasi-static hybrid simulation was conducted on a steel truss structure. A single truss member was considered as the physical substructure, while the remaining members were modeled using Abaqus finite element software. The communication between the physical and numerical models was established using OpenFresco as a middleware. Using this setup, the structure was loaded until the physical substructure failed due to buckling. Finally, the results of the hybrid simulation were verified numerically and experimentally.

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  • 48.
    Ali Qahtan, Nawar
    et al.
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Donna, Sojeva
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    En alternativ mötesplats i modern arbetsmiljö2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Studien behandlar utformning av en tillbyggnad som länkas samman med en befintlig byggnad och en planerad byggnad. Det på uppdrag av Videum AB som planerar att bygga ett nytt kontorshotell på Videum Science Park och vill ha en interstruktur som innehåller restaurang, reception och konferensrum. Denna tillbyggnad ska bli mötesplatsen för Videums personal, hyresgäster och för allmänheten.

    Resultatet visar ritningar, illustrationer och förklaringar över interstrukturen.

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  • 49.
    Ali, Sharafat
    et al.
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology. Corning Inc, USA.
    Paul, Biplab
    Linköping University.
    Magnusson, Roger
    Linköping University.
    Broitman, Esteban
    Linköping University.
    Jonson, Bo
    Linnaeus University, Faculty of Technology, Department of Built Environment and Energy Technology.
    Eklund, Per
    Linköping University.
    Birch, Jens
    Linköping University.
    Synthesis and characterization of the mechanical and optical properties of Ca-Si-O-N thin films deposited by RF magnetron sputtering2017In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 315, p. 88-94Article in journal (Refereed)
    Abstract [en]

    Ca-Si-O-N thin films were deposited on commercial soda-lime silicate float glass, silica wafers and sapphire substrates by RF magnetron co-sputtering from Ca and Si targets in an Ar/N-2/O-2 gas mixture. Chemical composition, surface morphology, hardness, reduced elastic modulus and optical properties of the films were investigated using X-ray photoelectron spectroscopy, scanning electron microscopy, nanoindentation, and spectroscopic ellipsometry. It was found that the composition of the films can be controlled by the Ca target power, predominantly, and by the reactive gas flow. Thin films in the Ca-Si-O-N system are composed of N and Ca contents up to 31 eq. % and 60 eq. %, respectively. The films thickness ranges from 600 to 3000 nm and increases with increasing Ca target power. The films surface roughness varied between 2 and 12 nm, and approximately decreases with increasing power of Ca target. The hardness (4-12 GPa) and reduced elastic modulus (65-145 GPa) of the films increase and decrease with the N and Ca contents respectively. The refractive index (1.56-1.82) is primarily dictated by the N content. The properties are compared with findings for bulk glasses in the Ca-Si-(Al)-O-N systems, and it is concluded that Ca-Si-O-N thin films have higher values of hardness, elastic modulus and refractive index than bulk glasses of similar composition. (C) 2017 Elsevier B.V. All rights reserved.

  • 50.
    Alijagic, Denis
    Linnaeus University, Faculty of Technology, Department of Building Technology.
    Att uppnå god energiprestanda: En jämförelse av teoretiska energiberäkningar och verklig energianvänding i småhus2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    En studie som utfördes på uppdrag av Norrköpings kommun med syfte att undersöka varför energideklarationer visar en annan specifik energianvändning gentemot energiberäkningar. Ett stickprov togs där tio småhus energiberäkningar och energideklarationer analyserades. Dessutom genomfördes intervjuer med tre medelstora kommuner (Norrköpings-, Linköpings- och Jönköpings kommun) samt Boverket för att lokalisera möjliga fel och förbättringar gällande Boverkets Bygg Regler, BBR. Boverkets föreskrifter och allmänna råd om fastställande av byggnadens energianvändning vid normalt brukande och ett normalår, BEN, togs även i beaktande att lokalisera felkällor i upprättade energiberäkningar för hus 1-10.

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